This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To advance human embryonic stem cell-derived dendritic cells towards clinical application for treatment of blood disease. We established an in vitro system for efficient differentiation of hESCs into myeloid DCs. We cocultured hESCs with OP9 stromal cells to induce their differentiation into myeloid progenitors. To produce DCs, we expanded hESC-derived myeloid progenitors in presence of GM-CSF. We generated myeloid progenitors that had CD4+CD11b+CD11c+ CD16+ CD123lowHLA-DR- phenotype and expressed myeloperoxidase. Further culture of myeloid cells in serum free media with GM-CSF and IL-4 generated cells that had typical dendritic morphology, expressed high level of MHC class I and II molecules, CD1a, CD11c, CD80, CD86, DC-SIGN and CD40. The hEC-DCs were capable of uptaking and processing antigen, as determined by DQ ovalbumin assay, triggering na[unreadable]ve T cells in MLR and presenting antigen to specific T cell clones through MHC class I pathway. The overall goal of this ongoing project is to apply the described model for identification of myeloid DC precursors and pathways regulating their expansion. This research used WNPRC stem cell resources and federally approved hES cell lines.